Barnett Annie K, Hussein Omar, Alghalayini Maher, Hinojos Alejandro, Nathaniel James E, Medlin Douglas L, Hattar Khalid, Boyce Brad L, Abdeljawad Fadi
Department of Materials Science and Engineering, Johns Hopkins University, Baltimore, Maryland 21218, United States.
Department of Physics and Astronomy, George Mason University, Fairfax, Virginia 22030, United States.
Nano Lett. 2024 Aug 7;24(31):9627-9634. doi: 10.1021/acs.nanolett.4c02395. Epub 2024 Jul 29.
We present large-scale atomistic simulations that reveal triple junction (TJ) segregation in Pt-Au nanocrystalline alloys in agreement with experimental observations. While existing studies suggest grain boundary solute segregation as a route to thermally stabilize nanocrystalline materials with respect to grain coarsening, here we quantitatively show that it is specifically the segregation to TJs that dominates the observed stability of these alloys. Our results reveal that doping the TJs renders them immobile, thereby locking the grain boundary network and hindering its evolution. In dilute alloys, it is shown that grain boundary and TJ segregation are not as effective in mitigating grain coarsening, as the solute content is not sufficient to dope and pin all grain boundaries and TJs. Our work highlights the need to account for TJ segregation effects in order to understand and predict the evolution of nanocrystalline alloys under extreme environments.
我们展示了大规模原子模拟，其揭示了铂 - 金纳米晶合金中的三叉晶界（TJ）偏析，这与实验观察结果一致。虽然现有研究表明晶界溶质偏析是使纳米晶材料相对于晶粒粗化在热学上稳定的一种途径，但在此我们定量表明，正是对三叉晶界的偏析主导了这些合金所观察到的稳定性。我们的结果表明，对三叉晶界进行掺杂会使其固定不动，从而锁定晶界网络并阻碍其演化。在稀合金中，研究表明晶界和三叉晶界偏析在减轻晶粒粗化方面效果不佳，因为溶质含量不足以对所有晶界和三叉晶界进行掺杂和钉扎。我们的工作强调了考虑三叉晶界偏析效应对于理解和预测纳米晶合金在极端环境下演化的必要性。
